EGF receptor-mediated intracellular calcium increasein human hepatoma BEL-7404 cells

Epidermal growth factor （EGF） induced intracellular free calcium ([Ca2+]i) response was studied in fura-2- or fluo-3-loaded human hepatoma cells of BEL-7404 cell line. Single cell [Ca2+]i analysis and [Ca2+], measurement in cell populations revealed that EGF triggered a rapid [Ca2+]iincrease in the dose-dependent and time- dependent manner. Pretreatment of cells with an endoplasmic reticulum （ER） Ca2+-ATPase inhibitor, thapsigargin （TG） at 100 nM concentration for 20 min, completely abolished EGF-induced [Ca2+]i increase, and chelating extracellular calcium by excess EGTA partially inhibited the increase.Furthermore, the expression of antisense EGF receptor sequence in BEL-7404 cells suppressed the [Ca2+]i response to EGF. The results suggest that EGF receptor-mediated [Ca2+]i increase in the human hepatoma cells is essentially dependent on the Ca2+ storage in ER.